Pulsed-field magnetisation of Y-Ba-Cu-O bulk superconductors fabricated by the infiltration growth technique

Abstract

Bulk high temperature superconductors based on the rare-earth copper oxides can be used effectively as trapped field magnets capable of generating large magnetic fields. The top-seeded infiltration growth (TSIG) processing technique can provide a more homogeneous microstructure and therefore more uniform superconducting properties than samples grown using conventional melt growth processes. In the present investigation, the properties of bulk, single grain superconductors processed by TSIG and magnetised by the pulsed-field magnetisation technique using a copper-wound solenoid have been studied. A trapped field of ∼3 T has been achieved in a 2-step buffer-assisted TSIG-processed Y-Ba-Cu-O (YBCO) sample at 40 K by magnetising the bulk superconductor completely via a single-pulse magnetisation process. Samples were also subjected to pulsed-field magnetisation at 65 K and by conventional field-cooled magnetisation at 77 K for comparison. Good correlation was observed between the microstructures, critical current densities and trapped field performance of bulk samples fabricated by TSIG and magnetised by pulsed-field and field-cooled magnetisation. The homogeneous distribution of Y2BaCuO5 inclusions within the microstructure of bulk YBCO samples fabricated by the 2-step buffer-assisted TSIG process reduces inhomogeneous flux penetration into the interior of the sample. This, in turn, results in a lower temperature rise of the bulk superconductor during the pulsed-field magnetisation process and a more effective and reliable magnetisation process.

High Critical Current Density of Nanostructured MgB2 Bulk Superconductor Densified by Spark Plasma Sintering

“…The voids, disorders and impurities present in the material can behave as pinning centers that hamper the vortex motion and minimize energy dissipation. Unlike cuprate superconductors [ 6 , 7 ], the J c values of MgB 2 can be strongly enhanced by increasing the number of grain boundaries while decreasing the grains’ size [ 8 , 9 ]. Although its transition temperature is relatively low for many applications (39 K), the processing conditions of MgB 2 -based materials are simpler and much cheaper than those of the cuprate superconductors.…”

Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications

“…This can be seen in Figure 13 where, for a large commercial ring segment-shaped GdBaCuO bulk, a weak area of superconductivity can be seen during a field cooling magnetization at 77 K. Another method for preparing large size single crystal is the so-called infiltrationgrowth technique. This method requires a matrix of precursor materials, a liquid reactive material, and like for the TSMG, a seed on the top of the bulk [60][61][62]. Contrary to the TSMG method, it is easy to control the shape and the density of the precursor matrix and so the characteristics of the prepared superconducting bulk.…”

Comparative calculations of trapped field and trapped magnetic flux with different multi-pulse magnetization methods for a bulk high-temperature superconductor

“…In order to improve the trapped magnetic field and the trapped magnetic flux (Φ ), various techniques of PFM have been developed, for example, multi-pulse field magnetization (M-PFM) methods [11,[15][16][17][18][19][20][21][22][23][24], waveform control pulse magnetization (WCPM) method [12,25], etc. In the WCPM method, an Insulated Gate Bipolar Transistor (IGBT) is used as a high-speed switch and the waveform of the magnetizing pulse is modified by changing the switching frequency of the IGBT [12].…”

“…The M-PFM methods, such as the successive magnetic pulse application (SPA) [18], the iteratively magnetizing pulsed-field method with reducing amplitude (IMRA) [19], the modified multi-pulse technique with step-wise cooling (MMPSC) [20], the MMPSC + IMRA method [21] and the SPA + IMRA method [22], can trap stronger magnetic field and larger magnetic flux for bulk superconductors compared with the single-pulse PFM. PFM is generally performed by applying a magnetic field using either a solenoid, vortex or split coil configuration [10,11,23,24].…”